Who Benefits From Fbx - SABINE FBX1220 Operating Instructions Manual

Of course, many savvy sound engineers, realizing the limitations of
graphic equalizers in removing problem feedback, prefer to use a
different type of equalizer, called a parametric EQ, for such applica-
tions. If you're one such audio engineer, you'll be comforted to know
that FBX filters share much in common with parametrics.
Compared to graphic filters, parametrics allow more precise adjust-
ments — specifically, control of filter width, the amount of boost or
cut, and the mid-band frequency of the filter. This greater precision,
however, comes at a price, as parametric filters are not nearly as
intuitive or simple to use as graphic equalizers.
Nothing, however, is easier to use than an FBX filter, which enjoys
the precision of a parametric filter, yet deploys instantly and auto-
matically whenever feedback is detected. Effectively, an FBX filter is
a parametric filter set to a tenth-octave width, restricted to cut-only
activity, and automatic in its choice of frequency band.
7 .3.1. Dynamic FBX Filters
Dynamic FBX filters also set automatically, but can change frequency, on a rotating basis,
as the need arises. To help distinguish dynamic from fixed filters, consider the example
of a speaker using a wireless lavalier microphone, who walks under a ceiling speaker for
the first time. In so doing, he enters a location-specific feedback zone, where it's possible
that a problem frequency may have escaped detection and notching by a fixed filter. If
all fixed filters have been deployed, a dynamic filter will be set automatically as soon as
feedback appears, solving the problem. Great! But what happens when the speaker then
moves away from the ceiling speaker, and close to a floor monitor? Feedback from the
ceiling speaker is no longer a problem, but a new frequency starts to squeal. If all fixed
and dynamic FBX filters are already set, a dynamic filter will change, to adjust to the new
location. An FBX dynamic filter thus stands guard if new problem feedback arises after
all available filters have been set, providing a deeper and more flexible level of protection
against the dreaded surprise of feedback. Other than the ability to change frequency, a
dynamic filter is equivalent to a fixed filter.
7 .3.2. Balancing Fixed & Dynamic Filters
Your FBX1220, and each channel of your FBX2420, offer a total of 12 FBX filters (com-
bined fixed and dynamic), which can be used as needed to exterminate feedback. After
years of experience and experimentation, Sabine has settled upon a default balance of
9 fixed and 3 dynamic filters, set at the factory. This default condition can be changed to
any combination you require.
If you follow setup instructions for setting FBX filters, your FBX1220/FBX2420 will automati-
cally exit SETUP mode (enter READY status) after all fixed filters and the first dynamic
filter are set. In the default condition, this means you will have set ten filters (nine fixed
and one dynamic), with two dynamic filters not set and ready to catch new feedback. If
you wish to set fewer filters, press the READY button before SETUP automatically exits,
after you have set enough filters to safely achieve your desired gain level. In that case, in
the factory default condition, you will have three dynamic filters plus the remaining unused
(and unlocked) fixed filters available to catch new feedback.
7 .3.3. FBX Filter width
Sabine's experience and testing with filters and sound quality led us to decide upon a
default FBX filter width of .10 (one-tenth) octave as the optimal notch width. This elimi-
nates feedback very well without affecting music programs. If, with all filters properly set,
feedback is still a problem, FBX filters may be set to .20 (one-fifth) octave width. This
wider filter setting will potentially control more feedback frequencies, especially when they
are clustered, but this wider filter may also affect music programs slightly. For this reason
the wider setting is generally considered to be appropriate where speech (less demanding
than music) is the primary application. You can change FBX filter widths by pressing the
FIFTH OCTAVE button on the front panel. Note that the width of any filter will always be
determined by the position of the switch at the time the filter is created.

7 .4. who Benefits from FBX?

Virtually every sound system will be improved with the Sabine feedback control. Singers
and presenters who do not have sound technicians can now increase their monitor or house
system volume so they can hear themselves clearly and with full fidelity, without worrying if
their microphones will suddenly squeal if they move to the wrong place.
Auditoriums and churches of all sizes will enjoy reliable feedback control. Hotels and confer-
ence centers around the world can offer meeting rooms with microphones that won't howl
during programs. Sabine FBX systems can be installed in theaters, schools, sports arenas,
courtrooms, teleconferencing rooms, intercoms or interactive remote classrooms — anywhere
one or multiple microphones are used.
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